Electronic devices can generate significant heat during use. Part of the electrical energy used to operate the device may be converted into heat energy. Depending upon the amount of heat energy created and the construction of the device, it may be necessary to provide for the dissipation of the heat energy to prevent damage to the device and/or provide for proper operation.
By way of example, lamps or other electronic devices that include solid state light emitting sources such as e.g., light emitting diodes (LEDs) can provide certain advantages over incandescent type lamps including better energy efficiency and longer life, but these light sources typically require management of certain heat related issues. The junction temperature for a typical LED device, for example, should be below 150° C. and in some LED devices should be below 100° C. or even lower. At these low operating temperatures, radiative heat transfer to the surrounding environment is weak compared with that of conventional light sources.
With electronic devices such as LED light sources that need heat management, the convective and radiative heat transfer to the environment can be enhanced by the addition of a heat sink. A heat sink is a component providing a large surface for radiating and convecting heat away from the electronic device. In a typical design, the heat sink is a relatively massive metal element having a large engineered surface area, for example, by having fins or other heat dissipating structures on its outer surface. Where equipped with a large surface area, the heat fins can provide heat egress by radiation and convection.
However, even with the use of a heat sink, significant challenges remain for sufficient heat dissipation from an electronic device such as e.g., a lamp. For example, depending upon the amount of light intensity desired, multiple light emitting devices such as LEDs may be desirable. Depending upon e.g., the number of such light emitting devices that are employed, the total thermal power, and other factors, the heat sink alone may not be able to adequately dissipate heat from the lamp through passive means. While increasing the size of the heat sink could improve the dissipation of heat, such may be undesirable because it may also increase the overall size of the electronic device. For example, increasing the size of a heat sink used with a lamp may cause the lamp to exceed specifications for form such as e.g., the ANSI A19 profile.
Additionally, some light emitting devices have directional limitations that also present challenges for lamp design. For example, LED devices are usually flat-mounted on a circuit board such that the light output is substantially along a line perpendicular to the plane of the circuit board. Thus, a flat LED array typically does not provide a uniformly distributed, omnidirectional light output that may be desirable for many lamp applications, However, the ability to arrange LEDs so as to provide a more uniformly distributed light output can also be limited by heat management issues that can negatively affect the arrangement that is otherwise optimal for light distribution.
Another challenge relates to aesthetics. An electronic device such as a lamp that is designed only with consideration of performance requirements regarding light output, energy usage, thermal management, etc. may not provide an appearance that is pleasing to e.g., certain consumers. Such can affect the marketability of lamp even if it otherwise performs well.
Accordingly, an active cooling device that can provide cooling for electronic devices such as e.g., lamps, circuit boards, and others would be useful. Such a device that can also be used compactly and/or discreetly—i.e. without undesirably increasing the size of the electronic device or negatively affecting the aesthetics of the device would also be useful.